My Internet service provider said that sometimes macs will not pull up certain websites because they are not formatted right.
True. Some web page designers do not check their design on Mac browsers. Therefore some web pages may not render properly. However, this is not too common.
If you don't mind my asking, what is the URL of the site you are having a problem with. Others in this forum can then see if they have the same problem.
Cheers, Tom 😉
P.S. What model Mac do you have and are you using OS 10.3.9?